Abstract
Tungsten nitride (W2N) was synthesized from WO3 and NH3 by means of temperature-programmed nitridation, and its activities for NO dissociation as well as NO reduction with H2 were evaluated. In a 5% H2/1% NO/He stream at 400°C, stable NO conversion to N2 of ca. 82% was observed within a test period of 40h. When the H2/NO ratio was reduced to 3/1, the conversion was ca. 80% and the catalyst started to deactivate after 28h of on-steam time. At a H 2/NO ratio of 1/1, NO conversion to N2 was ca. 63% and such performance could last for only 23h; even in the absence of H2, a conversion of ca. 52% lasted for 22h. We applied the XRD and XPS techniques, respectively, to examine the structural and compositional changes of W 2N during the reactions. The results indicated that the gradual loss in catalytic activity was due to the bulk oxidation of W2N into WO3. Combined the activity measurements with those of NO adsorption studies, we deduce that W2N is catalytically active for NO adsorption and dissociation, and a H2/NO ratio of 5/1 is required to avoid heavy accumulation of surface oxygen and deactivation of the catalyst.
Original language | English |
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Pages (from-to) | 819-826 |
Number of pages | 8 |
Journal | Catalysis Today |
Volume | 93-95 |
DOIs | |
Publication status | Published - 1 Sept 2004 |
Event | Selections from the Presentations of the 3rd Asia-Pacific Congress - Dalian, China Duration: 12 Oct 2003 → 12 Oct 2003 |
Scopus Subject Areas
- Catalysis
- General Chemistry
User-Defined Keywords
- NO dissociation
- NO reduction
- Tungsten nitride